SYRACUSE, N.Y. -- Deke Sharon, musical director of the Sing-Off Live! Tour, hit the ground running when he landed in Syracuse over the weekend. Sharon has been rehearsing three a cappella groups for the tour's first show at 8 p.m. Tuesday at Turning Stone Resort Casino. The tour features singers from past seasons of the "The Sing-Off," NBC's talent show competition for a cappella groups. Performers on the tour are Season 5 finalists The Exchange, Season 2 winners Street Corner Symphony and Season 4 winners VoicePlay.

Sharon knows people have come to appreciate a cappella through "The Sing-Off" on TV and "Pitch Perfect" (2012) at movie theaters, but they are missing something. "A cappella is best live. But, the experience is seeing it in person (that) is most impressive and impactful and wonderful about it," said Sharon, who is the vocal producer for the TV show and vocal arranger/producer for the movie.

The tour's show includes individual group performances as well as battles between all three groups and ensemble opening, closing and encore numbers. Performers' songs will span 70 years of music and include the tunes of Chuck Berry, Elvis, The Beatles to those on today's hit charts.

Speaking by phone from his home in San Francisco, Sharon said the human voice is the most varied instrument we have. "The thing that the human voice can do that no instrument can is it can make you laugh or cry within seconds. It's definitely the most expressive instrument. And I think the beauty of having all voices onstage stands in great contrast to the incredible amount of mechanization of current popular music," he said.

"When people hear a cappella I think they're reminded of their humanity and the beauty that comes from people and the human voice. There's a simplicity and a spirituality and a honesty that you can't find when you hear a stack of synthesizers."

Besides his involvement with TV, movies and tours, Sharon has performed in a cappella groups since his college days at Tufts University and the New England Conservatory of Music in Boston. Sharon, 47, now performs with House Jacks. He described a cappella as "singing without a net." He believes this feat distinguishes "The Sing-Off" on TV from other talent show competitions with solo singers backed by perfectly tuned orchestras.

"With the 'Sing-Off,' every single sound and every single movement on stage is coming from these individual singers, and one person gets off and the whole thing could fall apart like a house of cards. Which is why the complexity level, the difficulty level is the order of magnitudes higher than what happens on other reality shows. And when it happens just right, it's like a beautiful synergy between the moving parts," he said. "It's transcendent, it's beautiful to watch."

So Sharon has spent the past few days working with the tour's three groups to ensure the house of cards will stand up for Tuesday's show and the 54 cities to come on the schedule. At Turning Stone, Overboard, a Boston-based a cappella group, will open the show and perform at a few stops along the tour.